Euglenoids are single cellular organisms with euglena. Majority of them are fresh water organisms found in stagnant water. Instead of a cell wall, they have a protein rich layer called pellicle which makes their body flexible. They have two flagella, a short and a long one. Though they are photosynthetic in the presence of sunlight, when deprived of sunlight they behave like heterotrophs by predating on other smaller organisms.

Interestingly, the pigments of euglenoids are identical to those present in higher plants. They hoard their food as carbohydrate such as paramylum bodies.